But this has been met with strong opposition in parliament, with several Tory backbenchers vowing to oppose the legislation.

They say that nailing down an exact cut-off date could end up leaving Britain worse off.

The government has signalled it will seek a “transition period”, with much of the existing arrangements continuing for a limited time after March 2019.

This will allow for detailed talks on a future trade deal – potentially extending Brexit negotiations for years to come.

How do the Brexit negotiations work?

Delegations from the UK and EU meet regularly to thrash out decisions over separating the UK from European institutions and laws.

The UK wanted to negotiate post-Brexit deals at the same time as working through the divorce talks.

But the EU insisted on a different timetable – refusing to discuss trade until a number of issues are settled first.

This so-called phase one includes the Brexit “divorce bill” – how much Britain should pay to honour existing commitments.

The two other main issues are the rights of EU citizens and the border between Northern Ireland and the Republic of Ireland.

Only once the other 27 states decide “sufficient progress” has been made on phase one, can negotiations begin on phase two – the future relationship including a possible trade treaty.

Under the leadership of Prime MinisterTheresa May, the UK side of Brexit negotiations is led by David Davis, Secretary of State or Exiting the European Union.

He is deputised by Sir Tim Barrow, UK Permanent Representative to the EU, while beneath them is an army of civil servants.

Boris Johnson, the Foreign Secretary, and Liam Fox, Secretary of State for International Trade, is also be part of the effort to secure post-Brexit trade deals.

The EU delegation is led by Michel Barnier, the European Commission’s chief negotiator.

Alongside him is Jean-Claude Juncker, Commission President, Donald Tusk, European Council President, Guy Verhofstadt, European Parliament negotiator and Antonio Tajani, President of the European Parliament.